Mouthwash compositions are liquid preparations which are formulated to cleanse and refresh the oral cavity.
Cosmetic mouthwashes usually contain water, alcohol, flavor and color ingredients, and have excellent consumer acceptance because the rinse medium has a refreshing mouthfeel, and the residual mouthwash ingredients have a pleasant aftertaste.
A wide variety of mouthwashes are available which contain various combinations of beneficial ingredients such as astringents, deodorants, antibacterial agents, healing agents, analgesics, buffers, humectants, surfactants, flavorants, preservatives, and the like.
It is desirable to include sodium bicarbonate as an ingredient in a mouthwash formulation because it provides deodorizing and buffering activities, and it contributes a clean mouthfeel and refreshing aftertaste in the oral cavity.
However, the effective inclusion of an alkali metal bicarbonate ingredient in a mouthwash has been limited by practical considerations. An alkali metal bicarbonate compound has a low level of solubility in an aqueous alcoholic solvent medium, so that any content of alkali metal bicarbonate in a typical mouthwash formulation is limited to less than about 2 weight percent. Further, a liquid mouthwash formulation containing a dissolved content of alkali metal bicarbonate does not have long term storage stability. The alkali metal bicarbonate ingredient in an aqueous alcoholic mouthwash formulation tends to discompose to alkali metal carbonate and carbon dioxide under storage conditions. Alkali metal carbonate has an irritating effect on the surfaces of an oral cavity.
Accordingly, it is an object of this invention to provide a liquid mouthwash formulation which contains up to 20 weight percent and higher of alkali metal bicarbonate ingredient.
It is another object of this invention to provide a liquid mouthwash formulation which contains a particulate suspension of alkali metal bicarbonate ingredient, and which exhibits superior dimensional stability under long term storage conditions.
Other objects and advantages of the present invention shall become apparent from the accompanying description and examples.
Of special background interest with respect to the present invention are publications which describe mouthwash and other dentifrice formulations containing alkali metal bicarbonate, such as U.S. Pat. Nos. 4,370,314; 4,657,758; 4,861,582; and 5,145,664.